Merge pull request #450 from ceaess/master

Improve Which Python section grammar

docs/starting/which-python.rst

@@ -20,38 +20,37 @@ The Future (Python 3)
 
 `Further Reading <http://wiki.python.org/moin/Python2orPython3>`_
 
-Python 3, on the other hand, differs much more greatly from Python 2, so
-writing code that works both on Python 2 and Python 3 is a very complicated
+The difference between Python 3 and Python 2 is much greater, therefore
+writing code that works in both Python 2 and Python 3 is a very complicated
 process.
 
-It is still possible to `write code that works on Python 2.6, 2.7 and 3.3
-<http://lucumr.pocoo.org/2013/5/21/porting-to-python-3-redux/>`_. Depending on
-the kind of software you are writing, this might be either tricky or extremely
-hard, and if you're a beginner there are much more important things to worry
-about.
+It is possible to `write code that works on Python 2.6, 2.7 and 3.3
+<http://lucumr.pocoo.org/2013/5/21/porting-to-python-3-redux/>`_. This
+ranges from tricky to extremely hard depending upon the kind of software
+you are writing; if you're a beginner there are far more important things to
+worry about.
 
 Implementations
 ~~~~~~~~~~~~~~~
 
-There are several popular implementations of the Python programming language on
-different back-ends.
+When people speak of *Python* they often mean not just the language but also
+the CPython implementation. *Python* is actually a specification for a language
+that can be implemented in many different ways.
 
 CPython
 -------
 
 `CPython <http://www.python.org>`_ is the reference implementation of Python,
 written in C. It compiles Python code to intermediate bytecode which is then
-interpreted by a virtual machine. When people speak of *Python* they often mean
-not just the language but also this implementation. It provides the highest
+interpreted by a virtual machine. CPython provides the highest
 level of compatibility with Python packages and C extension modules.
 
 If you are writing open-source Python code and want to reach the widest possible
-audience, targeting CPython is your best bet. If you need to use any packages
-that rely on C extensions for their functionality (e.g., numpy) then CPython
-is your only choice.
+audience, targeting CPython is best. To use packages which rely on C extensions
+to function, CPython is your only implementation option.
 
-Being the reference implementation, all versions of the Python language are
-available as CPython.
+All versions of the Python language are implemented in C because CPython is the
+reference implementation.
 
 PyPy
 ----
@@ -63,19 +62,18 @@ features a just-in-time compiler and supports multiple back-ends (C, CLI, JVM).
 PyPy aims for maximum compatibility with the reference CPython implementation
 while improving performance.
 
-If you are looking to squeeze more performance out of your Python code, it's
+If you are looking to increase performance of your Python code, it's
 worth giving PyPy a try. On a suite of benchmarks, it's currently `over 5 times
 faster than CPython <http://speed.pypy.org/>`_.
 
-Currently PyPy supports Python 2.7. PyPy3 which targets Python 3 was recently
-available as a beta release. [#pypy_ver]_
+PyPy supports Python 2.7. PyPy3 [#pypy_ver]_, released in beta, targets Python 3.
 
 Jython
 ------
 
 `Jython <http://www.jython.org/>`_ is a Python implementation that compiles
-Python code to Java bytecode that is then executed in a JVM. It has the additional
-advantage of being able to import and use any Java class like a Python
+Python code to Java bytecode which is then executed by the JVM (Java Virtual Machine).
+Additionally, it is able to import and use any Java class like a Python
 module.
 
 If you need to interface with an existing Java codebase or have other reasons to
@@ -88,7 +86,7 @@ IronPython
 
 `IronPython <http://ironpython.net/>`_  is an implementation of Python for the .NET
 framework. It can use both Python and .NET framework libraries, and can also
-expose Python code to other .NET languages.
+expose Python code to other languages in the .NET framework.
 
 `Python Tools for Visual Studio <http://ironpython.net/tools/>`_ integrates
 IronPython directly into the Visual Studio development environment, making it